Present regulations in many jurisdictions require that doors in public building have at least a twenty minute fire rating. This rating provides that the door should act as a fire break to prevent passage of the fire through the door for at least a period of twenty minutes. Some jurisdictions also have regulations requiring upgrading of fire protection ratings of existing doors in existing buildings either at time of renovation of the space or, in some cases, within a fixed period of time. Up to the present time, in order to upgrade the fire protection rating of the door, it has been necessary to replace the existing door by a new fire rated door. In some instances, replacement of such doors may be difficult and may require replacement of the frame of the doors as well. In addition, in unique historic buildings, the replacement of the doors is also difficult due to the unique value of the existing doors. It would thus be desirable to have a means of upgrading existing doors in a building to the proper fire rating.